/*
 * fromucs.c - convert Unicode to other character sets.
 */

#include "charset.h"
#include "internal.h"

struct charset_emit_param {
  char *output;
  int outlen;
  const char *errstr;
  int errlen;
  int stopped;
};

static void charset_emit(void *ctx, long int output)
{
  struct charset_emit_param *param = (struct charset_emit_param *)ctx;
  char outval;
  char const *p;
  int outlen;

  if (output == ERROR) {
    p = param->errstr;
    outlen = param->errlen;
  } else {
    outval = output;
    p = &outval;
    outlen = 1;
  }

  if (param->outlen >= outlen) {
    while (outlen > 0) {
      *param->output++ = *p++;
      param->outlen--;
      outlen--;
    }
  } else {
    param->stopped = 1;
  }
}

int charset_from_unicode(const wchar_t **input,
                         int *inlen,
                         char *output,
                         int outlen,
                         int charset,
                         charset_state *state,
                         const char *errstr,
                         int errlen)
{
  charset_spec const *spec = charset_find_spec(charset);
  charset_state localstate;
  struct charset_emit_param param;

  param.output = output;
  param.outlen = outlen;
  param.stopped = 0;

  /*
   * charset_emit will expect a valid errstr.
   */
  if (!errstr) {
    /* *shrug* this is good enough, and consistent across all SBCS... */
    param.errstr = ".";
    param.errlen = 1;
  }
  param.errstr = errstr;
  param.errlen = errlen;

  if (!state) {
    localstate.s0 = 0;
  } else {
    localstate = *state; /* structure copy */
  }
  state = &localstate;

  while (*inlen > 0) {
    int lenbefore = param.output - output;
    spec->write(spec, **input, &localstate, charset_emit, &param);
    if (param.stopped) {
      /*
       * The emit function has _tried_ to output some
       * characters, but ran up against the end of the
       * buffer. Leave immediately, and return what happened
       * _before_ attempting to process this character.
       */
      return lenbefore;
    }
    if (state)
      *state = localstate; /* structure copy */
    (*input)++;
    (*inlen)--;
  }
  return param.output - output;
}
